I use Strava for running, synced with health app, and i often have doubled entries on the walking+running distance field.
the only solution i have so far is to manually delete one of the two entries (or maybe it's an issue with strava, i contacted support but still have to get an answer).

also, starting from 9.3, when viewing on weekly, monthly or yearly base, you always get the "daily average" score, while on earlier releases it was the total distance for the relative unit (eg. in yearly view: 9.2 showed the total monthly distance in each bar, 9,3 shows the daily distance averaged per month...).
As a runner i was more satisfied with the previous method of display, but for "walk activity" i understand it's hard to get a feeling of what it means to walk say 250km per month.

Is it possible that you have an app that is also recording steps and updating HA's database? I had a similar issue with an app (sorry, don't recall which one I was trying at the time) that was recording pretty much same data, so, double totals. Along these lines, I've noticed some apps when they get updated, might be changing their background app refresh option: maybe something similar for HA apps (Settings > Privacy > Health)

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